Abdominal exercises are a set of movements designed to strengthen abdominal muscles. There are many different techniques, which can be divided into lower and upper abdominal exercises. The most common exercises are "crunches" or "sit-ups."

Abdominal muscles are commonly activated by active flexion of the trunk through a concentric muscle contraction. Strong abdominal muscles help stabilize the trunk and unload lumbar spine stress.

The trunk flexion can be measured by the distance from the sole of the foot to the tip of the finger when an individual is bending forward without bending the knees.

A recent American Council on Exercise study, evaluated 13 of the most common abdominal exercises and ranked them. Among the most effective were the bicycle maneuver, the captain's chair, crunches done on an exercise ball, crunches done with the legs held vertically, and reverse crunches.

General abdominal exercise guidelines: Most experts recommend several (3-5) abdominal exercises 2-3 times a week with at least a days rest in between each workout. Two sets of 10-15 repetitions for each exercise are recommended in the beginning. With improvement, an individual may increase to 3 sets of 20 repetitions. Doing all of the exercises is not necessary; individuals may select 3-5 exercises initially and vary this routine over the months.

Bicycle maneuver: Lie on the back with knees bent and feet flat on the floor. Place fingertips on the side of the head just behind the ears. Push the lower back into the floor, flattening the arch and hold. Bring the knees up to about a 45-degree angle and slowly go through a bicycle pedaling motion. Touch the left elbow to the right knee, then the right elbow to the left knee. Breathe evenly throughout the exercise.

Captain's chair: This exercise requires a captain's chair, which allows an individual to lift his bent legs toward his upper body. tart with the legs dangling and slowly lift knees in toward the chest. The motion should be controlled and deliberate as the knees are brought up. Return to the starting position.

Crunch on an exercise ball: Sit on the exercise ball with feet flat on the floor. Let the ball roll back slowly and lie back until thighs and torso are parallel with the floor. Contract the abdominal muscles raising the torso to no more than 45 degrees. To work the oblique muscles, make the exercise less stable by moving the feet closer together.

Basic crunch: Lie on the back with the knees bent and feet flat on the floor. Place fingertips on the side of the head just behind the ears. Push the lower back into the floor, flattening the arch and hold. Curl up slowly so both shoulders lift off the floor a few inches. Hold for a count of two, and return to the start position. Note: Do not clasp fingers behind the head. Do not tuck the chin to the chest. Keep the head up. Eyes should stay focused on the ceiling.

Half curl: Lie on the back with the knees bent and feet flat on the floor. Place the palms on the thighs and curl up until fingertips reach the knees and breathe out. Return to the start position. Tips: Do not tuck the chin to the chest. Keep the head up.

Vertical leg crunch: Lie on the back with the knees bent and feet flat on the floor. Place fingertips to the side of the head, just behind the ears. Push the lower back into the floor, flattening the arch and hold. Extend the legs straight up in the air, crossed at the ankles with a slight bend in the knee. Contract the abdominal muscles by lifting the torso toward the knees. Exhale when contracting upward; inhale when returning to the start. Tip: Do not tuck the chin to the chest.

Reverse crunch: Lie on the back with knees bent and feet flat on the floor. Place fingertips to the side of the head just behind the ears. Crossing the feet at the ankles, lift the feet off the ground to the point, creating a 90-degree angle with the knees. Push the lower back into the floor, flattening the arch and hold. The hips will slightly rotate and the legs will reach towards the ceiling with each contraction. Exhale when contracting; inhale when returning to the start.

Alternating 'Supermans': Lie face down on a mat with the arms stretched above the head (like superman). Raise the right arm and left leg about 5-6 inches off the ground. Hold for three seconds and relax. Repeat with the opposite arm and leg.

Plank: Lie face down on a mat with elbows right next to the chest, palms facing down. Push off the floor, rising up onto toes and elbows with palms flat, back flat angling up from toes to shoulders. Hold abdominals tight, and keep the spine neutral. Tilt the pelvis and contract the abdominals to prevent the buttocks from sticking up in the air. Hold for 30 to 60 seconds, and then lower; repeat.

Crossover crunches: Lie on the back with the knees bent and feet flat on the floor. Cross the right leg over the left leg so the right ankle is resting on the left knee. Place the fingertips to the side of the head just behind the ears. Begin a crunch, but twist the torso and touch the left elbow to the right knee. Return to the starting position and repeat for the desired number of repetitions before switching over to the other side.

Side bends: Holding a dumbbell in the right hand, stand with the feet shoulder-width apart and the knees slightly bent. Place the left hand behind the head and slowly bend sideways to the right, lowering the dumbbell down to the knee. Return to an upright position and repeat for the desired number of repetitions.

Medicine ball sit-ups: Lie on the back with the knees bent and feet flat on the floor. Hold a medicine ball (a five-pound ball is recommended for beginners) to the chest and have a partner stand at the feet (not on them). Push the lower back into the floor, flattening the arch and hold.

Simultaneously curl up and throw the ball to the partner. Hold the crunch as the partner catches the ball and throws it back. Catch the ball and slowly return to the start position.

In recent years, obesity has been linked to many health conditions, including, hypertension, dyslipidemia and dysglycemia. Attention has also focused on the importance of abdominal (or central) obesity as a determinant of cardiovascular risk, independent of the body mass index.

Exercise training has been found to reduce total and abdominal fat. These changes in body composition mediate improvements in insulin sensitivity and blood pressure and may improve endothelial vasodilator function.

Although exercise improves fitness, the reductions in total and abdominal fatness and increase in leanness are more strongly associated with favorable changes in risk factors for cardiovascular disease and diabetes, including those that constitute metabolic syndrome.

The information in this monograph is intended for informational purposes only, and is meant to help users better understand health concerns. Information is based on review of scientific research data, historical practice patterns, and clinical experience. This information should not be interpreted as specific medical advice. Users should consult with a qualified healthcare provider for specific questions regarding therapies, diagnosis and/or health conditions, prior to making therapeutic decisions.